Bushing contact

ABSTRACT

The invention relates to a socket contact ( 1 ) including a back-up spring ( 3 ) and a base spring ( 2 ), the back-up spring ( 3 ) enclosing the base spring ( 2 ) in box-like manner with a first wall ( 11 ), a second wall ( 12 ), a third wall ( 13 ) and a divided fourth wall ( 14 ). The wall sections ( 14   a,    14   b ) of the fourth divided wall ( 14 ) are connected to each other in positive fitting manner. On one wall section ( 14   a ), there are formed at least two connecting lugs ( 23 ) arranged in the front and rear portions of the wall section ( 14   a ) as seen in the direction of insertion of the socket contact ( 1 ). The other wall section ( 14   b ) is formed with a recess ( 24 ) for each connecting lug ( 23 ), and the connecting lugs ( 23 ) are passed through the recesses ( 24 ) and bent over. For increased stability, the two wall sections ( 14   a,    14   b ) overlap over the full length of the back-up spring ( 3 ).

BACKGROUND OF THE INVENTION

The invention relates to a socket contact consisting of a back-up springand a base spring, the back-up spring enclosing the base spring inbox-like manner with a first, second, third and a divided fourth wall,and with at least two connecting lugs being formed on one wall sectionfor connecting the wall sections of the fourth divided wall to eachother in positive manner, said connecting lugs, in the direction ofinsertion of said socket contact, being formed in the front and rearportions of the wall sections.

SUMMARY OF THE INVENTION

Such a back-up spring is known from DE 195 36 500 C2. The back-up springis made of a stamped and bent part, with the two top wall sections beingseparated from each other by a longitudinal slot for manufacturingreasons. One of the top wall sections, in the lower partial region ofthe longitudinal slot, is formed with a connecting lug that is bentupwardly from the top wall section by a cranked portion and extendsbeyond the longitudinal slot in the direction towards the opposite topwall section and overlaps the other top wall section. The connection ofthe connecting lug to the other top wall section takes place either byplastic forming, i.e. plastic cold forming and pressing the connectingportion into each other using a punch, or by welding or by a completelypositive connection. The publication does not suggest a concretepositive connection of the top wall sections.

DE 43 12 641 A1 discloses an electric contact bushing comprising aback-up spring in which the back-up spring also has a longitudinal slotin its bottom wall for manufacturing reasons. The bottom wall sectionshave abutment edges which extend in parallel along the longitudinal slotand which are not aligned in the front region of the contact bushing butrather establish a hook-type design.

This kind of positive connection, however, has the disadvantage that thehook-type connection may be released in case of strong torsion ormechanical load of the back-up spring.

Furthermore, DE-UM 92 01 047 discloses a double flat spring contactcomprising a back-up spring integrally incorporated in the contact andformed in one piece with the same. The base part of this contact isdivided, with the thus formed side walls being connected to each otherwith stability in terms of shape via two connecting lugs. The connectinglugs have a recess and a dovetail-like projection, respectively, that iswedged into said recess.

This type of connection also entails the disadvantage that it may becomereleased in case of torsion or strong mechanical loads acting on theback-up spring.

It is thus the object of the invention to indicate for a socket contactof the type indicated at the outset a back-up spring having an as stableas possible closed box-shape that can be manufactured without additionalworking expenditure.

This object is met according to the invention in that the other wallsection is formed with a recess for each connecting lug and that theconnecting lugs are passed through the recesses and bent over, and thetwo wall sections overlap over the full, length of the back-up spring.

This type of connection can easily be produced on a stamping and bendingmachine. The connecting lugs to this end are bent over first by 90° sothat they protrude outwardly. Thereafter, the other wall section withthe recesses is bent over the protruding connecting lugs such that theconnecting lugs extend through the recesses. By bending over the upperportion of the connecting lugs, the wall halves of the divided fourthwall are connected to each other with stability in shape.

Due to the fact that the wall halves overlap over the entire length ofthe back-up spring, a closed box-shape is obtained and the stability ofthe connection is increased considerably. By said overlapping, the upperwall section is clamped between the bent portion of the connecting lugsand the lower wall section. The clamping effect adds a frictionalcomponent to the positive connection.

The wall halves thus are firmly connected to each other both in thelongitudinal and in the transverse direction of the back-up spring. Alsoin case of high mechanical loads, such as e.g. torsion or stepping-onloads of the back-up spring, there is thus no risk that the connectionof the wall halves will become disengaged.

The recesses preferably are formed in the upper wall section in the formof elongate holes. At least one recess, however, may also be formed asU-shaped recess on the terminal-side or contact-side edge of the upperwall section.

The provision of the recesses in the form of elongate holes has theadvantage that the connecting lugs, after bending, can be formed into ashape such that they are supported on the walls of the recesses.

The deformation of the connecting lugs suitably takes place by pressingtogether or introducing one or more notches on the upper side of theconnecting lugs.

To enclose the base spring in as stable manner as possible, it isnecessary to keep the contact area between back-up spring and basespring as large as possible. To this end, the upper wall section, infront of the overlapping portion, is advantageously formed with a crankwith the material thickness of the lower wall section.

Further advantageous developments are indicated in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated in more detail hereinafter by way of anembodiment depicted in the drawings, in which

FIG. 1 shows a perspective view of a socket contact looking onto thedivided fourth wall;

FIG. 2 shows a corresponding view of the socket contact looking onto thefirst wall;

FIG. 3 shows a perspective view of a further modification of the back-upspring looking onto the divided fourth wall;

FIG. 4 shows a cross-sectional view of a contact cavity of a contactcarrier receiving a socket contact; and

FIG. 5 shows a partial sectional view of the contact region of thesocket contact.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate a socket contact 1 consisting of a base spring2 and a back-up spring 3. The entire socket contact 1 is inserted into acontact cavity 4 of a contact carrier 5 (cf. FIG. 4), e.g. a sockethousing of an electrical connector assembly with single-row or multi-rowcontact cavities. The base spring 2 is formed with a terminal section 6,e.g. in the form of a crimp-type terminal, for an electric conductor andwith a contact section 7 having a spring leg base 8 of e.g. U-shaped orrectangular design in cross-section, from which extend the spring legs 9and 10 (cf. FIG. 5) for establishing contact with a plug-type contact,e.g. a contact blade. The spring legs 9 and 10 of the base spring 2originate, in the disclosed embodiment, from the top and bottom wall ofa spring leg base 8 of rectangular cross-section. The spring legs may bedesigned as ordinary forked spring arms or double flat spring contacts,but may also have a plurality of contact lamellas on each spring leg byproviding longitudinal slots. In case of the socket contact 1illustrated, each spring leg 9, 10 has four contact lamellas.

The back-up spring 3 also is of rectangular cross-section so that itencloses the entire contact section 7 of the base spring 2 with fourwalls 11 to 14 in box-shaped manner. The first wall 11 constitutes thetop wall, the second and third walls 12, 13 constitute the side walls,and the fourth wall 14 represents the bottom wall. In the lower partialregion of the first wall 11 facing the terminal section 6 of base spring2, there is formed an outwardly bent locking hook 15 as primary lockingfeature for a socket contact 1 to be inserted into a contact cavity 4 ofcontact carrier 5. Locking hook 15, on its outer face side in the middlethereof, has an outwardly projecting bulge 16 and is provided with animpressed portion 17 on both sides of the bulge 16. Due to the impressedportions 17, there are formed relatively sharp edges on the face side oflocking hook 15 which contribute in that the locking hook 15 providesfor better fixation of the socket contact 1 in the contact cavity 4. Theoutwardly directed bulge 16 in locking hook 15 also contributes inproviding improved fixation of socket contact 1 in contact cavity 4.

For providing the effect that the looking hook 15 is pressed against theinner wall of contact cavity 4 as strongly as possible, there isprovided a reinforcing bead 18 in the bending line between the lockinghook 15 and the first wall 11. The reinforcing bead 18 aggravatesbending back of the looking hook 17 towards tie first wall 11.

For fixing the back-up spring 3 on the base spring 2, the second andthird walls 12, 13 of back-up spring are formed with folding lugs 19, 20formed by separating cuts, which engage in corresponding openings 21, 22the side walls of the spring leg base 8.

The base spring 2 and the back-up spring 3 are stamped and bent sheetmetal members and thus are divided into two in one wall formanufacturing reasons.

In case of back-up spring 3, the fourth wall 14 is divided into two andconsists of the two wall sections 14 a and 14 b. For obtaining a stableclosed box-shape, the wall sections 14 a and 14 b are connected to eachother in the manner elucidated hereinafter.

The wall sections 14 a and 14 b overlap over the entire length ofback-up spring 3. Due to such overlapping, there is formed a lower wallsection 14 a and an upper wall section 14 b. The lower wall section 14 ahas two connecting lugs 23 formed thereon which are bent upwardly by 90°and are passed through corresponding recesses 24 in the upper wallsection 14 b. For providing a positive or form-fit connection of thewall sections 14 a and 14 b, the connecting lugs 23, after having beenpassed through the recesses 24, are bent over once more by 90° so thatthe upper wall section 14 a is clamped between the bent over upperportion of the connecting lugs 23 and the lower wall section 14 a.

In bending over the upper portion of the connecting lugs 23, these arepress-fit such that the connecting lugs 23 are urged against the sidewalls of opening 24. By doing so, any possibility of movement of thewall sections 14 a and 14 b relative to each other is excluded afterpress-fitting. In addition to or as an alternative to press-fitting, thetop sides of the bent over connecting lugs 23 may be provided withnotches 25 so that the connecting lugs become broader in thelongitudinal direction of the back-up spring 3 and are also pressedagainst the side walls of the recesses 24. The notches 25 are arrangedperpendicularly to the longitudinal direction of the back-up spring 3.

The two connecting lugs 23, through which wall sections 14 a and 14 bare connected to each other, are arranged substantially in the front andrear portions of the lower wall section 14 a as seen in the direction ofinsertion of socket contact 1.

The connecting lug 23 located closer to the terminal section 6 of thebase spring 2 is of considerably broader configuration and is providedon the top side thereof with two or more notches 25.

In order for the back-up spring 3 to enclose the rectangular base spring2 almost completely, the upper wall section 14 b is bent by a crank 26in front of the portion overlapping with the lower wall section 14 a.

On the face side of the lower wall section 14 a facing in insertiondirection, there is arranged an additional lug 27 that is also bentupwardly by 90°, and the somewhat broader upper portion thereof isfolded back downwardly by 180°. The upper folded portion of lug 27constitutes a polarizing member 28 for the socket contact 1, so as toprevent erroneous insertion of the socket contact into the contactcavity of a contact carrier. Lug 27 is laterally offset from thelongitudinal axis of the back-up spring 3. The upper folded portion isbroadened in the direction towards the longitudinal axis of the backupspring 3, but still is arranged laterally offset from the longitudinalaxis of the back-up spring 3. However, it may also be arranged centrallywith respect to the longitudinal axis of the back-up spring 3 so as tobe matable with the contact cavity 4 as shown in FIG. 4. As shown by thesectional view in FIG. 4, the contact cavity 4 of contact carrier 5 isformed with a corresponding polarizing groove 29 for polarizing member28.

In order to not hinder insertion of socket contact 1 into the contactcavity 4 of contact carrier 5, the dimensions of polarizing member 28transversely of the direction of insertion are smaller than those of thepolarizing groove 29.

On the divided fourth wall 14 and on the first wall 11 of the back-upspring 3, there is formed, for each spring leg 9, 10 of the back-upspring 3, an inwardly bent back-up spring tongue 30 which abut on thespring legs 9, 10 approximately at the height of the contact region 31(cf. FIG. 5).

FIG. 3 shows an additional modification of the back-up spring 3. Theconnection of wall sections 14 a and 14 b is effected both on theterminal side and on the contact side via two connecting lugs 23 ofequal width, which are provided with only one impressed portion 25 eachon their top side. The terminal-side recess 24 in upper wall section 14a is of U-shaped configuration. The locking hook 15 is formed on theterminal-side edge of the first wall 11 and is produced by two cuts 32,33 starting from the face side of the first wall 11 that is directedtowards terminal section 6.

1. A socket contact comprising a base spring and a discrete backup spring, said base spring comprised of at least two opposed contact portions attached to a conductor connecting portion, said backup spring enclosing the base spring in box-like manner with a first wall, a second wall, a third wall, and divided fourth wall, and with at least two connecting lugs being formed on one wall section for connecting the wall sections of the divided fourth wall to each other in positive manner, said connecting lugs being arranged in the front and rear portions of the wall section as seen in the direction of insertion of the socket contact, the other wall section is formed with a recess for each connecting lug and said connecting lugs are passed through the recesses and bent over, and the two wall sections overlap over the full length of the backup spring, said backup spring further comprising backup spring arms positioned proximate to said opposed contact portions in an overlying manner.
 2. The socket contact of claim 1, wherein a lower wall section and an upper wall section are formed by said overlapping of the wall sections of the backup spring, and the connecting lugs are formed on the lower wall section and the recesses are formed on the upper wall section.
 3. The socket contact of claim 2, wherein at least one recess is formed as an elongate hole in the upper wall section.
 4. The socket contact of claim 2, wherein at least one recess is formed as U-shaped recess on the terminal-side or contact-side edge of the upper wall section.
 5. The socket contact of claim 2, wherein the upper wall section, in front of said overlapping portion, has a crank with the material thickness of the lower wall section.
 6. The socket contact of claim 2, wherein the lower wall section is formed with a polarizing member.
 7. The socket contact of claim 1, wherein the connecting lugs, after being bent over, are deformed such that they are supported on the walls of the recesses.
 8. The socket contact of claim 7, wherein the deformation of the connecting lugs is effected by press-fitting or introducing one or more notches on the upper side of the connecting lugs.
 9. The socket contact of claim 1, wherein a locking hook extending in the longitudinal direction of the backup spring is cut out and bent outwardly from the first wall.
 10. The socket contact of claim 1, wherein, for mounting the backup spring on the base spring, there are formed folding lugs on the opposing second and third walls of the backup spring, with said folding lugs being adapted to be bent inwardly and engaging in corresponding openings on the base spring.
 11. A socket contact comprising a base spring and a discrete backup spring, said base spring comprised of at least two opposed contact portions attached to a conductor connecting portion, said backup spring consisting of a different metal than said base spring and enclosing the base spring in box-like manner with a first wall, a second wall, a third wall, and a divided fourth wall comprised of overlapping wall portions, and with at least two connecting lugs being formed on one of said overlapping wall portions and complementary recesses being formed in said other overlapping wall portion, said connecting lugs being passed through the recesses and bent over for connecting the wall sections of the divided fourth wall to each other in positive manner, said connecting lugs being arranged in the front and rear portions of the wall section as seen in the direction of insertion of the socket contact, said backup spring further comprising backup spring arms positioned proximate to said opposed contact portions in an overlying manner.
 12. The socket contact of claim 11, wherein a lower wall section and an upper wall section are formed by said overlapping of the wall sections of the backup spring, and the connecting lugs are formed on the lower wall section and the recesses are formed on the upper wall section.
 13. The socket contact of claim 12, wherein at least one recess is formed as an elongate hole in the upper wall section.
 14. The socket contact of claim 12, wherein at least one recess is formed as U-shaped recess on the terminal-side or contact-side edge of the upper wall section.
 15. The socket contact of claim 12, wherein the upper wall section, in front of said overlapping portion, has a crank with the material thickness of the lower wall section.
 16. The socket contact of claim 12, wherein the lower wall section is formed with a polarizing member.
 17. The socket contact of claim 11, wherein the connecting lugs, after being bent over, are deformed such that they are supported on the walls having the recesses.
 18. The socket contact of claim 17, wherein the deformation of the connecting lugs is effected by press-fitting or introducing one or more notches on the upper side of the connecting lugs.
 19. The socket contact of claim 11, wherein a locking hook extending in the longitudinal direction of the backup spring is cut out and bent outwardly from the first wall.
 20. The socket contact of claim 11, wherein, for mounting the backup spring on the base spring, there are formed folding lugs on the opposing second and third walls of the backup spring, with said folding lugs being adapted to be bent inwardly and engaging in corresponding openings on the base spring. 